We also record all inputs of mulch, ash, compost and water applied to the bed.
If you would like to learn more about comfrey and why it's considered such a great plant by many people take a look at our previous post Comfrey - BELIEVE the HYPE!. To find out the results from this year's trials read on.
Comfrey Patch Overview
Location - Our Market Garden, Shipka, Bulgaria
Climate: Continental Temperate
Average Annual Rainfall: 588.5mm
Co-ordinates: 42.71259, 25.32575
Species/Cultivar - Symphytum x uplandicum 'Bocking 14'
The patch was prepared in the spring of 2015. Two 13m2 beds were allocated to the comfrey but only 1 bed was used to take records. For instructions on how to set up a comfrey patch see our previous article here
Following taking a soil sample from the area we dug over the plot, removing weeds and added 20 L of mature compost per metre length of bed (200L) and 70g of wood ash per metre length (700g). We planted out the beds using divided crowns of larger plants and left them to grow without disturbance for the entire season. We also broadcast approx. 1.5g per m2 of Trifolium repens onto the pathways between the beds.
Planting Material - It's easy to plant out with crown divisions or root cuttings in the spring when the soil has warmed. A crown division can be obtained from simply putting a spade through the center of a mature comfrey plant and transplanting the divided sections. For our patch I divided 2 yr old plants into quarters, sometimes sixths, and these established very well in the first year. We did not harvest the leaf biomass in the first year in order to allow a deep root system to develop. However if you use large divisions you can start harvesting in July.
Irrigating - Irrigation was applied to the beds every 10-14 days without rain which this season was from mid June - mid October - almost 15 weeks without a significant rainfall. We use flood irrigation diverted into the paths from mountain stream. I'd estimate 30 L per m length each week without rainfall would be sufficient.
Cutting - We cut the Comfrey four times this season (see below for dates and weights). The comfrey is cut to approx 5 cm from the ground using a sickle, shaken out so all of the wildlife drops out and weighed immediately.
Mowing - After the cut the pathways and surrounding paths are mown and the trimmngs are applied more or less evenly to the surface of the bed.
Preparing Liquid Fert - The fresh material is stuffed into a 200 L barrel with stones on the top to compress the material and left to decompose for a few weeks. The result is a black smelly slurry that can be sieved off to leave a quantity of dark brown liquid. The liquid can then be diluted from 1-15 to 1-20 and applied to crops. The largest cut we made from 13m2 bed just about fit into the 200 L barrel.
We left the plants to flower for 7-10 days before each cut, seeing as the bees were so into the flowers. This probably resulted in lower yields and next year we intend to cut before flowering and plant extra plants nearby solely for the bees and other pollinating insects.
From the 13m2 patch we harvested a total of 96.92kg of comfrey leaves. This was obtained from four cuts.
- For higher yields the plants should be cut before flowering. We did not carry out this practice as the bees found the flowers so attractive.
- I believe we could also increase yields by applying urine fertiliser and we will experiment with this in the future. This would be particularly useful if growing the comfrey for animal fodder or mulch for perennial plants.
- We used most of the comfrey for making a liquid fertilsier for our market garden crops. We produced 47 L of concentrate that can be mixed 1-15 with water. We applied the dilute at a rate of 500ml per plant to tomato plants when setting fruit. The last batch we used for mulch and covered an area of 4m2 with approx 11.5kg of material. Comfrey can also be used to feed animals. Our rabbits and pigs both enjoy the fresh material and we use plants growing in our garden around the animal housing for this.